i have it running fine, just got a new ngk sparky, new boot and got the carby cleaned out, it was going easily 47-52 kmh now it maxs out like 35-40 going flat but down hill obviously i gain power, was actually running it about 70 kmh last night, but yes i get to full throttle and it feels like its vibrating more and theres a significant power loss, any fix ive just broken the motor in ive been running it on 50:1 like the builder told me to use and that seems fine, not sure about the whole ruch/lean thing any thoughts?